The vibrational spectra including matrix isolation, conformations and ab initio calculations of 4-azidobut-1-yne

摘要: Abstract 4-Azidobut-1-yne can exist in five distinct conformations denoted GG, GG′, GA, AG and AA according to the gauche anti conformation around C–C C–N bonds, respectively. Fully optimised ab initio geometries for all conformers have been calculated at MP2(full)/TZ2P//MP2(full)/TZ2P level. The conformational energies were GG (0), (+1.24 kJ mol −1 ), (+1.50 kJ mol GG′ (+3.35 kJ mol ) GA (+3.75 kJ mol ). Additional single point calculations also performed MP4(DSQ)/TZ2P//MP2(full)/TZ2P level conformers. IR spectra of molecule obtained vapour liquid states room temperature as amorphous crystalline solids nitrogen temperature. argon matrices recorded, applying hot nozzle technique with temperatures between 313 600 K. Raman range 232–295 K a solid 148 K measured. A number strong bands disappeared crystal phase. same increased their relative intensity upon annealing low suggesting that most stable conformer is not one present Apparently, are matrix 12 K, whereas only three (GG, AA) observed matrix. phase isolation showed very small variations it was possible estimate energy differences To assist spectral assignment, force fields scaled using six scale factors. results suggest well GG.